Carburetor apparatus

ABSTRACT

Carburetor apparatus for vaporizing and mixing a liquid fuel with a stream of gas. An incoming stream of gas is directed through an annular venturi. The outlet ends of a plurality of circumferential spaced-apart fuel jet tubes project into the throat portion of the venturi. The fuel jet tubes have their inlet ends in communication with a supply of fuel confined within a reservoir. Elongate inserts mounted within the tubes are radially spaced from the tube inner surfaces to define relatively small cross sectional area capillary fuel flow passageways. The inserts are adapted for both vertical and lateral displacement to dislodge any foreign matter which forms or deposits within the tube passageways. The end of each insert which projects into the fuel reservoir is reversely bent to form an enlarged portion serving to limit the vertical displacement of the insert.

United States Patent Coverston July 24, 1973 CARBURETOR APPARATUS PrimaExaminer-Tim R. Miles [76] Inventor: George C. Coverston 76 S. Russell 7r r r 9 r r St, Fallon 89406 Attorney-Paul D. Flehr, Robert B. Block eta1. [22] Filed: Apr. 21, 1972 [57] ABSTRACT [2]] A l N 246,258Carburetor apparatus for vaporizing and mixing a liquid fuel with astream of gas. An incoming stream of gas is directed through an annularventuri. The outlet ends [52] US. Cl. 261/1, 261/DIG. 39, 223691/7ll186,of a plurality of circumferential spaced apafl fuel jet 51 I Cl F02 ()4tubes project into the throat portion of the venturi. The l 1 IG fueljet tubes have their inlet ends in communication [58]. e o catch l D I 3with a supply of fuel confined within a reservoir. Elon- 261/1 239,118gate inserts mounted within the tubes are radially spaced from the tubeinner surfaces to define relatively [56] Reerences Cited small crosssectional area capillary fuel flow passage- UNITED STATES PATENTS ways.The inserts are adapted for both vertical and latl,360,265 11/1920Capell 239/118 cral displacement to dislodge any foreign matter which1,399,655 12/ 192! Rector 2391118 forms or deposits within the tubepassageways. The end 1,460,667 1923 Good 39 of each insert whichprojects into the fuel reservoir is gubbard reversely bent to form anenlarged portion serving to merson 3,325,975 6/1967 Coverston.... 55/225the vemcal "Splacemem the i 3,567,124 3/1971 Jones 239/ 118 2 Claims, 2Drawing Figures PAIENIED JUL24|915 l caasusaros srmaa'rns BACKGROUND OFTHE INVENTION Carburetors of known construction utilize variousexpedients to introduce and vaporize a liquid fuel into an incoming flowof air to form a combustible charge for induction into an internalcombustion engine. In these known carburetors, a venturi flow passage isformed with metering fuel jets discharging into the air stream at thethroat portion of the venturi.

In US. Pat. No. 3,325,975 issued to the present applicant, a carburetoris provided which creates a high degree of fuel vaporization and hasprovision for removal of fuel droplets through centrifugal action. Theapparatus of the patent includes means forming an annular venturi with aplurality of circumferentially spaced-apart tubes or fuel nozzlesarranged with their inlet ends disposed in the fuel supply and withtheir outlet ends disposed in the venturi throat. The mixture ofvaporized fuel and air is directed by baffle means through a reverseflow path arranged to remove fuel droplets by centrifugal action so thata substantially droplet free combustion charge is inducted into theengine.

The tubular fuel jets utilized in known carburetors of the typedescribed are subject to failure or reduced effectiveness for reasonswhich include the fact that foreign matter and contaminants in the fuelstend to lodge in or form deposits on the surfaces of the fuel tube ornozzles. Among the foreign matter which may be found in fuels of thisnature are solid particulate matter such as dirt which may not beremoved by a fuel filter, and dissolved contaminants which may graduallyadhere to and form a gum or a varnish-like layer or deposit within theinner surfaces of the tube. The problem of foreign matter depositbecomes highly critical in carburetors employing relatively smalldiameter, capillary action fuel tubes of the type disclosed inApplicants issued Patent where a high degree of fuel atomization isachieved. The flow area of such capillary tubes is so small that thelikelihood of malfunction due to the presence of foreign matter isincreased substantially.

OBJECTS AND SUMMARY OF THE INVENTION This invention relates in generalto improvements in apparatus for forming a mixture of gas and avaporized liquid, and in particular relates to improvements incarburetor apparatus for atomizing or vaporizing liquid fuel for mixturewith a stream of air to form a combustible charge for induction into aninternal combustion engine.

It is a general object of the invention to provide carburetor apparatuswhich is effective to provide a high degree of liquid fuel atomizationin a stream of gas for more complete combustion of the inducted charge,and thereby reduced pollutants in the exhaust.

Another object of the invention is to provide carburetor apparatus whichefficiently atomizes and injects fuel into an air stream while at thesame time avoids functional failure of carburetor operation which couldotherwise occur as a result of any foreign matter contained in the fuel.

Another object of the invention is to provide carburetor apparatus ofthe character described utilizing fuel jet tubes in which insert membersare carried within the tubes to define capillary flow passagestherewith, with the inserts adapted to undergo limited vertical andaxial displacement to dislodge any foreign matter which may form ordeposit within the tubes.

The invention includes a carburetor apparatus in which an air stream isdirected through an inlet conduit into the throat of an annular venturi.A fuel supply reservoir is provided within the carburetor with aplurality of circumferential spaced-apart fuel jet tubes having inletends in communication with fuel in the reservoir and having outlet endsdisposed in the venturi throat. Elongate insert members mounted in eachof the tubes are radially spaced from the inner surfaces thereof todefine relatively small diameter fuel flow passages effective to providecapillaryaction for withdrawing fuel from the reservoir and to injectfuel into the air stream for relative complete fuel atomization so thatmore complete combustion is achieved. The elongate inserts are mountedin the tubes for both axial and lateral displacement to dislodge anyforeign matter which may form or deposit within the tubes. The ends ofthe inserts projecting into the reservoir are reversely bent to formenlarged portions for limiting the extent of axial displacement. Thegaseous mixture of vaporized fuel and air is directed by the carburetorhousing through throttle means for induction into an engine.

Additional objects and features of the invention will appear from thefollowing description in which the preferred embodiments of theinvention has been set forth in detail in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view inelevation of carburetor apparatus according to the invention;

FIG. 2 is a cross-sectional view to an enlarged scale of a fuel jet tubeand insert of the apparatus of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing FIG. 1illustrates generally at 10 carburetor apparatus constructed inaccordance with the invention. The preferred form of carburetorapparatus 10 comprises a downdraft type carburetor including acylindrical housing 11 extending from mounting flange 12 which in turnis secured by suitable fasteners such as bolts to an intake manifold,not shown, incorporated in the associated internal combustion engine. Anannular cover 13 is secured to the upwardly open end of housing 11 bymeans such as a plurality of fasteners 14 extending between brackets 16secured to the side of the housing and arms 17 secured to the cover. Anair inlet conduit 18 is mounted by fasteners 19 within a central openingformed in cover 13, and a suitable air cleaner, not shown, may beprovided upstream of the inlet conduit.

Air inlet conduit 18 directs an incoming stream of air verticallydownwardly into a chamber 21 formed within an upwardly open cylindricalstructure 22 comprising an outer cylindrical wall 23 and flat bottomwall 24. Cylindrical structure 22 is mounted by means of a bracketassembly 26 depending from within conduit 18. The inner surface ofcylindrical wall 23 is formed into an annular cusp-shaped configurationradially spaced about the outer periphery of inlet conduit 1E and withan upper portion 27 flaring outwardly from the conduit such thatupwardly directed venturi means 2a is formed having an annular throatportion 29 adjacent the cusp of the cylindrical wall. The stream of airflowing from chamber 21 and exiting from the venturi means is reversedin direction by cover 13 and housing 11 for downward flow through thepair of passageways 31, 32 leading to the intake manifold. Throttlemeans is provided which includes a pair of butterfly-type valves 33, 34mounted on a throttle shaft 36 for pivotal movement by means of asuitable throttle linkage, not shown.

A plate 37 having a circular recess 38 is mounted below bottom wall 24of the cylindrical structure through suitable fasteners 39 to define afuel supply reservoir 41. A suitable annular gasket 42 is provided toform a fluid-tight seal between the peripheral rim of the plate and thebottom wall. A liquid hydrocarbon fuel is supplied to the reservoirthrough a passageway 43 formed in the plate and connected through tubing44 with a float chamber assembly 46. The float chamber assemblycomprises a housing 47 defining a fuel chamber 48 having an inlet 49 incommunication with fuel supply fitting 51 and an outlet 52 incommunication with tubing 44. The float chamber housing is threadablymounted to the downwardly projecting end of the fitting which in turn ismounted through an opening in cover 13 and connected at its upwardlyprojecting end 53 with a fuel supply line, not shown. A longitudinallygrooved needle valve 54 is slidably mounted within housing inlet 49 formovement to and from a valve seat formed within fitting 51. The needlevalve directs fuel into the float chamber responsive to movement of afloat 56 carried within the chamber for maintaining the fuel supplysubstantially at the illustrated level 57.

Fuel jet means is provided to meter the fuel with a high degree ofatomization into the incoming stream of air. This fuel jet meanscomprises a plurality of upright, circumferentially spaced-apart hollowcapillary tubes 58, 59 mounted within openings 60 formed within bottomwall 24 in vertical alignment below venturi throat 29. Each of the tubeshas an inlet end 61 in fluid communication with the fuel supplyreservoir and an outlet end 62 disposed in the venturi throat. The level57 of the fuel within float chamber assembly 46 is established at anelevation which is below the level of the tube outlet ends.

As best illustrated in FIG. 2 an elongate rod-like insert 63 is mountedwithin each of the tubes. Preferably both the tubes and inserts arecircular in cross-section, although the invention contemplates thatother crosssectional configurations may be employed. The insert 63 isradially spaced from the inner cylindrical surface of the tube to definean annular fuel flow passageway 64 of a relatively small cross-sectionalarea which is effective to create a capillary effect for withdrawingfuel from the reservoir into the tube, and at the same time to create ahigh degree of liquid subdivision as the fuel is sprayed into the airstream for a relatively greater atomization and vaporization of thefuel.

The inserts are mounted within each tube for both axial and lateraldisplacement to dislodge any foreign matter which may form or depositwithin the small clearance between the insert and tube. Movement of theinsert in this manner effects both abrasive and mechanical actionagainst the foreign matter to prevent obstruction of passageway 64 andto ensure proper operation of the carburetor. Engine vibration andmovement is carried through to the carburetor to generate lateraldisplacement of the inserts. Axial displacement of the inserts isgenerated by changes in the static pressure differential between thetube inlet and outlet ends due to variations in air stream flow ratesthrough the venturi. Thus, an increased flow rate reduces the staticpressure at the venturi throat tending to both aspirate added fuelthrough the tubes and raise the insert to the broken line position ofFIG. 2. A decrease in the air flow rate reduces the static pressuredifferential so that the insert is moved by force of gravity downwardlyto the illustrated solid line position. Suitable means is provided tolimit the extent of axial displacement of the inserts, and this meanspreferably comprises an enlarged extension 66 of the insert disposedwithin the reservoir and which is formed by reversely bending the lowerend of the insert. This extension engages at its upper extremity withtube inlet end 61 to limit upward travel of the insert, and engages atits lower extremity with the surface of annular shoulder 67 formedwithin the recess of plate 37, as best illustrated in FIG. 1. The insertis sized to be of sufficient axial length so that it completely projectsthrough the tube throughout the range of its axial displacement.

In the operation of carburetor 10 when connected with the intakemanifold of an internal combustion engine, float chamber assembly 46feeds sufficient fuel through tubing 44 to completely fill supplyreservoir 41, with the fuel moving upwardly by capillary action intoeach of the fuel jet tubes 58, 59. Operation of the engine with thepumping action of its pistons inducts a stream of air downwardly throughinlet conduit 18 where it reverses for upward flow through venturi means28 and then again reverses for downward flow within housing 11 and isdirected into the engines intake manifold under control of throttlevalves 33, 34. The increased flow velocity of the air at venturi throat29 creates a reduced static pressure which acts to aspirate and meterfuel with a high degree of atomization from the outlet ends of fuel jettubes 58, 59. At the same time the static pressure differential acts onthe tube inserts moving them upwardly which, together with lateraldisplacement of the inserts as limited by the radial clearance withinthe tubes, serves to dislodge any foreign matter which may form ordeposit within the tubes. Fuel which is'withdrawn from reservoir 41 isreplenished from float chamber assembly 46 which in turn is replenishedby operation of float 56 and needle valve 54.

While the embodiment herein is at present considered to be preferred itis understood that numerous variations and modifications may be madetherein by those skilled in the art, and it is intended to cover in theclaims all such variations and modifications as fall within the truespirit and scope of the invention.

I claim:

1. In a carburetor for mixing a liquid fuel with a gas, the combinationof a conduit positioned to direct said gas into an incoming stream,means defining an annular venturi about said conduit, said venturihaving a throat portion for reducing the static pressure of said streamof gas, a reservoir spaced below said throat portion for containing asupply of fuel, a plurality of vertically elongate hollow tubes eachhaving an inlet end in fluid communication with fuel contained in saidreservoir and having an outlet end in discharge relationship with saidventuri throat portion, a plurality of elongate tube inserts, eachinsert being mounted in a respective one of said tubes and beingradially spaced from the inner surface thereof to define a capillaryfuel flow passageway, each insert being mounted for vertical and lateraldisplacement with respect to the tube inner surface associatedtherewith, and means to limit the vertical displacement of each insertbetween an upper position assumed under the influence of reduced staticpressure of 5 gas in said venturi throat portion and a lower positionassumed under influence of gravity acting on said insert.

2. In a carburetor apparatus, the combination comprising means forming areservoir containing a liquid fuel, means forming a continuouspassageway for directing a stream of gas through said carburetor, saidlast mentioned means including means forming a venturi having a throatportion, fuel jet means for directing fuel from said reservoir into saidstream of gas, said fuel jet means including one or more substantiallyvertically extending elongate tubes, each tube being formed with aninner cylindrical surface having a length extending between an inletdisposed in said reservoir in communication with said contained fuel andan outlet disposed in said venturi throat portion, an elongate insertcarried within each of said tubes and being radially spaced from saidinner cylindrical surface to define a fuel flow passageway therewith,means forming upper and lower spaced stop surfaces in substantiallyvertical register and disposed below said tubes, weight means formed onthe lowermost ends of each insert and disposed between said stopsurfaces, and means mounting each insert for movement axially within itsassociated tube between extrerne positions in which said weight meanscontacts, respectively, said upper and lower surfaces responsive to theresultant force acting on said insert from the force of gravity and thepressure force differential acting on the insert as a combination ofstatic gas pressure within said venturi and fuel pressure within saidreservoir whereby said movement of each insert dislodges any foreignmatter disposed in said flow passageway, each insert being sized inlength sufficiently greater than said length of the associated tubeinner cylindrical surface whereby the cross sectional area of the flowpassageway therebetween is independent of the axial position assumed bythe inserts with respect to the tubes.

1. In a carburetor for mixing a liquid fuel with a gas, the combinationof a conduit positioned to direct said gas into an incoming stream,means defining an annular venturi about said conduit, said venturihaving a throat portion for reducing the static pressure of said streamof gas, a reservoir spaced below said throat portion for containing asupply of fuel, a plurality of vertically elongate hollow tubes eachhaving an inlet end in fluid communication with fuel contained in saidreservoir and having an outlet end in discharge relationship with saidventuri throat portion, a plurality of elongate tube inserts, eachinsert being mounted in a respective one of said tubes and beingradially spaced from the inner surface thereof to define a capillaryfuel flow passageway, each insert being mounted for vertical and lateraldisplacement with respect to the tube inner surface associatedtherewith, and means to limit the vertical displacement of each insertbetween an upper position assumed under the influence of reduced staticpressure of gas in said venturi throat portion and a lower positionassumed under influence of gravity acting on said insert.
 2. In acarburetor apparatus, the combination comprising means forming areservoir containing a liquid fuel, means forming a continuouspassageway for directing a stream of gas through said carburetor, saidlast mentioned means including means forming a venturi having a throatportion, fuel jet means for directing fuel from said reservoir into saidstream of gas, said fuel jet means including one or more substantiallyvertically extending eLongate tubes, each tube being formed with aninner cylindrical surface having a length extending between an inletdisposed in said reservoir in communication with said contained fuel andan outlet disposed in said venturi throat portion, an elongate insertcarried within each of said tubes and being radially spaced from saidinner cylindrical surface to define a fuel flow passageway therewith,means forming upper and lower spaced stop surfaces in substantiallyvertical register and disposed below said tubes, weight means formed onthe lowermost ends of each insert and disposed between said stopsurfaces, and means mounting each insert for movement axially within itsassociated tube between extreme positions in which said weight meanscontacts, respectively, said upper and lower surfaces responsive to theresultant force acting on said insert from the force of gravity and thepressure force differential acting on the insert as a combination ofstatic gas pressure within said venturi and fuel pressure within saidreservoir whereby said movement of each insert dislodges any foreignmatter disposed in said flow passageway, each insert being sized inlength sufficiently greater than said length of the associated tubeinner cylindrical surface whereby the cross sectional area of the flowpassageway therebetween is independent of the axial position assumed bythe inserts with respect to the tubes.